start of labour?

So last night I woke up with period like cramps and my lower back killing me. I thought for sure it was the start of labour but I didn't have any clear indication of contractions it was just like cramping. I'm a FTM so i don't know what the begining of contractions feel like. so 2 hours later all the pain just stopped and it hasn't come back. I'm 39w5d, does this sound like the start of Labour? o also I had a lot of cervical mucus, I've already lost my mucus plug and I haven't had much cervical mucus in the third trimester so seeing this much is surprising, is that normal? Thanks for any feedback!